1. Field of the Invention
The present invention relates to a retractable wheel device of luggage, and more particularly, to an automatically retractable steering wheel device of a pullman case.
2. Description of Related Art
Luggage is commonly carried by travellers. Further, a luggage with wheels mounted is very popular among travellers in recent years. Generally, those luggage are equipped with two wheels. When in use, a traveller simply pulls a telescopic frame of a luggage up and then pulls it with a single hand. Such a luggage is much labor-saving as compared with the luggage lifted by a hand. However, such a luggage equipped with two wheels is simply designed for light weight occasion. With regard to the heavy luggages, a pullman case with four wheels mounted becomes available.
A prior art of a four-wheeled pullman case A is shown in FIG. 1. In general, a pullman case A comprises a telescopic frame B, a luggage body C, a wheel bracket D, two retractable swivelling wheels E, and two main wheels F. The main wheels F are mounted in two wheel housing F1 at the two rear lower corners of the pullman case A respectively; while the retractable swivelling wheels E are mounted between the main wheels F.
FIG. 2 is a perspective view of the pullman case A of FIG. 1 with the wheel bracket D extended. As illustrated, the swivelling wheels E are mounted on two bottom corners of the wheel bracket D respectively. The wheel bracket D has a supporting bracket D2, which is hinged to the luggage body C with a hinge D1, a retractable hinge D3 for drawing back or extending the supporting bracket D2, and two half spherical recesses D4 for receiving two retracted swivelling wheels E1.
It is commonly designed that the two wheel housing F1 of the main wheels F are fixed on the luggage body C. The wheel hub E2 and the swivelling wheels E1 are allowed to swivel together freely. The drawback of the pullman case A of the prior art is that the swivelling wheels E1 cannot be made to go back to the recesses D4 by simply retracting the wheel bracket D due to the fact that the swing angles of the swivelling wheels E1 are instantly arbitrary. This will cause the swivelling wheels E1 not to be aligned with the recesses D4. Resultantly, it is required to manually adjust the swivelling wheels E1 in order to retract them into the recesses D4.
Thus, it is desirable to provide an automatically retractable swivelling wheels device of a pullman case to overcome such drawback of the prior art.